This should not be a deep in depth study, rather group of little possible tricks so that direction might be given. You will need to pick and chose because as Colin said, not all is good for everybody. My example below.

First step – The key of C major scale where there are no flats or sharps.
1- C D E F G A B C
2- Place a number under each step of the scale.
C = I D = II E = III F = IV G = V A = VI B = VII

By using these numbers we can apply the same knowledge to every key.
Example; I in the key of C Major is a C --- I in the key of G Major is G
III in the key of C major is E -- III in the key of D Major is F#
If more information is needed email me.

Idea #1
Playing in the key of C Major – at the end of a song – G7 go to C Major chord
We can also write that as V7 going I

Whenever you are about to end a song, in this case in the key of C Major, the progression normally will be, but not always, G7 C or V7 I

In place of the V chord sub a bII7 chord. The bII7 refers to the second step of the C major scale which is D and making it a D flat and adding a 7th. You can also play the G7 (V7) and then play the Db (bII7) and end in with the C chord.

Future Ideas will not be the length of this post, the first steps will not needed to be written each time allow a much shorter post.

John C.